Method of making a tubular member by helically coiling a metallic strip, tubular member produced by this method and device for carrying out this method

ABSTRACT

A strip having hooked edges is laterally curved and coiled into a spiral in which the hooked edges of adjacent coils overlap. Just before the coils are overlapped the strip is formed into a helix the turns of which slant in a direction opposite to that of the turns of the helix finally formed so that when adjacent turns are forced into engagement with each other adjacent turns are resiliently biassed toward each other. The invention includes apparatus adapted to carry out this method and the tubular member produced thereby.

United States Patent Mazuir et al. 51 Dec. 26, 1972 [54] METHOD OFMAKING A TUBULAR [56] References Cited MEMBER BY HELICALLY COILING AMETALLIC STRIP, TUBULAR UNTED STATES PATENTS MEMBER PRODUCED BY THIS2,899,921 8/1959 Nicolaiser ..72 49 METHOD AND DEVICE FOR 3,478,40811/1969 Brown CARRYING OUT THIS METHOD 3,214,995 11/1965 Gilonore..29/505 X Inventors: Rene A. Mazuir; Daniel E. Hoffmann, both ofBourg-en-Bresse, France Assignee: Societe Anonyme Des Hauts Fourneaux DeLa Chiers, Longwy-Bas, France Filed: July 6, 1970 Appl. No.: 52,295

Foreign Application Priority Data Primary Examiner-Charles W. LanhamAssistant Examiner-R. M. Rogers Attorney-Holcombe, Wetherill & Brisebois[57] ABSTRACT A strip having hooked edges is laterally curved and coiledinto a spiral in which the hooked edges of adjacent coils overlap. Justbefore the coils are overlapped the strip is formed into a helix theturns of which slant in a direction opposite to that of the turns of thehelix finally formed so that when adjacent turns are forced intoengagement with each other adjacent turns are resiliently biassed towardeach other. The invention includes apparatus adapted to carry out thismethod and the tubular member produced thereby.

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FIG/IO SUMMARY OF THE INVENTION This invention relates to a new methodof manufacturing tubular articles by helically winding a shaped metallicstrip, to the new tubular members produced by 1 this method, and to theapparatus used in carrying out said method.

lt is the object of the present invention to provide tubular membersmade by the simple interfitting of shaped metallic strips and which havethe characteristic of possessing both great mechanical strength and asubstantial flexibility so that the tubular members may be wound up oncores of relatively'small diameter.

The tubular members according to the invention may be advantageouslyused as' flexible drill pipe in the drilling of oil wells.

When flexible drill pipe is used for this purpose a bit is mounted atthe end of a long tubular member having a certain flexibility, anddriven either by an electrical motor at the head of the well, andsupplied through electrical cables passing down through the tubularmember, or by a turbine driven by a fluid such as the mud which isforced under pressure into the flexible tubular member.

The great advantage presented by this new drilling process resides inthe fact that it is unnecessary to rotate the tubular member about itsaxis as it is progressively introduced into the ground, as is the casein conventional drilling methods.

Moreover, the fact that the tubular member is flexible makes it possibleto roll it up easily on drums of relatively small diameter. Thisconsiderably facilitates the operations of sending down and withdrawingtubular members which are always necessary for the maintenance andrepair of drilling bits.

The cylindrical members used for flexible drilling generally comprise aninternal tube of plastic material which seals the tubular member againstfluids which pass therethrough and provides a smooth inner surface whichfacilitates the flow of fluids. This internal tube must be locatedinside an equally flexible tubular member which is capable of resistingthe substantial mechanical stresses resulting from the high pressureswhich must prevail inside and outside the tubular member duringdrilling. This flexible tubular member may be made, in accordance withthe invention, from a helically coiled shaped metallic strip.

The tubular members according to the invention are then, in the case offlexible drilling tubes, covered by layers of wire wound thereabout, asin the case of cables, to insure the mechanical strength and resistanceto tension which are required.

The present invention proposes to provide tubular members which, whilesufficiently flexible, have a substantial mechanical strength so as tobe capable of resisting both internal and external pressure. Moreover,the tubular bodies according to the invention may be easily formeddirectly around the tube which is to constitute a fluid-tight seal.

The manufacture of tubular members of the type according to theinvention from strong shaped steel strips has already been suggested,using strips having the general form of a Z or an S.

However, it has not heretofore been possible to helically wind suchshaped strips under satisfactory conditions.

It has been found, in effect, that when an attempt is made to helicallywind a strip having an S or Z section by conventional methods thecohesion between the turns of the resulting tubular member isinsufficient. This results in poor mechanical strength, which renderssuch a tubular member completely unsuitablefor use as flexible drillingpipe.

It is the object of the present invention to provide a new process formanufacturing a flexible tubular member adapted to be used as flexibledrilling pipe from a strong shaped steel strip having an S or Z section.In accordance with this method a permanent arcuate deformation isimparted to the strip, so that the edge of the strip which, aftermanufacture of the tubular member, is outside the tubular member, islonger than the edge of the strip which, after manufacture of thetubular member, is inside thereof. After having first deformed themetallic strip in this manner, it is helically deformed to form thetubular member by engaging one edge of the strip over the edge of thelast-formed turn of the tubular member. This process is characterized bythe fact that the strip is given a shape such that it is resilientlybiassed against the last-formed turn of the tubular member.

For this purpose the shaped strip is given a natural helical shape in adirection opposite to that in which the tubular member is being formed.

The present invention is also directed to the new article of manufacturewhich consists of a tubular member made by helically winding a strong,shaped metallic steel strip having an S or Z shaped section inaccordance with the foregoing process, said tubular member beingprincipally characterized by an excellent resistance to internal andexternal pressure, by substantial flexibility which permits it to bewound on cores of relatively small diameter, and a perfectly cylindricalshape which it retains while being bent.

The present invention also relates to the new article of manufacturewhich consists of a flexible tube for use in drilling oil wellsessentially characterized by the fact that it comprises a strongflexible tubular steel member as above defined.

The present invention is also directed to a device for carrying out theforegoing process, which device is essentially characterized by the factthat it comprises in combination: means for bringing the shaped metallicstrip at a suitable speed into a plane substantially tangent to thetubular member which is being formed; means for imparting a permanentarcuate deformation to said strip, the side of the strip located in thedirection in which the tubular member is being formed having a lengthgreater than the other side of the strip; means consisting, for example,of forming fingers for imparting to said strip a helical deformationabout a diameter which corresponds substantially to the diameter of thetubular member, thus assuring the engagement of the coil being formedwith the coil which has just been formed; means for guiding the tubularmember formed in this manner, and means for synchronizing the rotationof the tubular member which has been formed and the arrival of the stripfrom which the tubular member is to be made.

The means for imparting an arcuate deformation to the strong steel stripmay advantageously consist of a set of rollers bending the strip beyondits elastic limit.

In one particular embodiment of'the invention, the means for imparting ahelical shape to the strip may advantageously consist of a forming headhaving a plate mounted through a universal joint on a framework so as tobe adjustable in its operating position by swinging it about both ahorizontal axis and a vertical axis.

This plate comprises a central orifice through which the tubular memberis formed. About the periphery of this orifice are means such as Tshaped notches to which the supports for the various forming fingers maybe attached.

In one embodiment of the invention the supports for the forming fingersmake it possible to regulate the angular orientation of the fingers withrespect to a direction radial to the tubular member and the distance ofthe fingers from the axis of the tubular member being formed.

Other properties and characteristics of the invention will appear in thecourse of the following description of a preferred embodiment of theinvention, which is being given purely by way of example, and withreference to the accompanying drawings, in which:

- FIG. 1 is a schematic elevational view of a machine for carrying outthe process according to the invention;

FIG. 2 is a top plan view of the machine of FIG. 1;

FIG. 3 is a schematic perspective view showing how the shaped memallicstrip is formed into a helix in accordance with the invention;

FIG. 4 is a partial sectional view of an enlarged scale taken throughthe axis of a tubular member manufactured in accordance with theinvention;

FIGS. 5, 7 and 9 are elevational view taken transversely ofthe axis of atubular member, and FIGS. 6,8 and 10 are corresponding side views takenduring various steps of the formation of the tubular member according tothe invention;

FIG. 11 is an elevational view taken transversely with respect to theaxis of the tubular member, showing the forming fingers and theirsupports; and

FIG. 12 is a schematic sectional view taken along the line 12-12 ofFIG.11.

' FIGS. 1 and 2 show the overall layout of a machine for carrying outthe process according to the invention. In particular, these figuresshow a reel 1 on which a tube of plastic material 2 is wound. This tubeis intended to constitute the inner lining of the tubular memberaccording to the invention. The reel 1 is mounted on a support 3 whichrotates about a horizontal axis.

Another reel 4 carries the tubular member 5 according to the inventionand is mounted on a support 6 which also rotates about a horizontalaxis.

The reel 4 is rotated with respect to the support 6 by a motor 7 througha conventional transmission 8, which is schematically shown.

The shaped high strength steel strip 9 is unwound from a reel 10rotatably mounted on a stationary support. This shaped strip 9, drivenby two pairs of rollers 11, reaches the forming head 12 after havingpassed over the rollers 13 which impart an arcuate shape to it.

The device for curving the shaped metal strip is shown on the otherfigures in a more detailed manner. Beyond the forming head the shapedstrip 9 is converted into the tubular member 5 which then passes througha traction cage 14 which-rotates about a horizontal axis and comprisesdriving rollers 15 which engage the tubular member 5 and drive it alongan axial path.

An electric motor 16 drives a shaft 17 through a set of pulleys andbelts. This shaft extends the full length of v the machine and controls,through reduction gearing 18 and belts or chains, the horizontalrotation of the support 6. a

It also controls, through reduction gearing 19, the rotation of thetraction cage 14, and through reduction gearing 20, the rotation of therollers 15 which axially advance the tubular member.

Similarly, the shaft 17 controls through reduction gearing 21 therotation of the pairs of rollers 11 which axially advance the strip 9.Finally, the shaft 17 drives the cage 3 through reduction gearing 22.

A brake 23, which is only schematically shown, restricts the unwindingof the plastic tube 2 which is coiled on the reel 4, after having beenencased in the tubular member manufactured in accordance with theinvention.

The speeds of rotation of the different members which have beendescribed are so determined as to coordinate the speed of rotation ofthe tubular member 5 and the speed at which the strip 9 advances to formthe member 5 in question.

The different components to which reference has been made have not beenindividually described in a more detailed manner because thesecomponents, when considered individually, are well known in the cablemanufacturing industry.

The device for carrying out the process according to the invention isshown in a more detailed manner on the perspective view of FIG. 3.

This figure shows the two pairs of rollers 11 which drive the strip 9 ata suitable speed. The section of this strip is shown on a larger scaleat the left of FIG. 3.

The rollers 11 have shapes such that the strip 9 is lead flat to thetable 24, which is provided with two forming rollers 13.

The axes of these rollers are mounted so that they turn freely and theirpositions may be adjusted by screw means 25, which are schematicallyshown. These rollers 13 cooperate with a third roller 26 designed toturn the strip 9 toward the forming head.

The forming head, which is indicated as a whole by reference numeral 12,consists of a plate 27 mounted by means of a universal joint on asupport 28.

This universal joint mounting permits the plate 27 to pivot on two arms29 about a horizontal axis 30. The plate 27 is attached to the arms 29by screws 31 seated in arms 29 and passing through semicircular holes 32in a member fixed to the plate 27.

This arrangement permits the position of the plate 27 to be easilyadjusted by pivoting it about the horizontal axis 30.

A second adjustment of the plate 27 with respect to a vertical axisresults from the fact that the arms 29 are connected to each other by across member 33 which is provided with oblong holes 34 through which thebolts 35 which attach the cross member 33 to the base 28 pass.

It will be understood that, under these conditions, by releasing thebolts 35, it is possible to pivot the cross member 33 slightly and thusturn the plate 27 about a vertical axis.

Finally, the cross-member 33 is mounted on bolts 35 between adjustablenuts which make it possible to adjust the height of the plate 27.

The plate 27 (which, as has already been explained, may be adjusted inall directions) comprises a central hole 36. The tubular member 5 whichis formed by the strip 9 passes through this hole.

The plate 27 comprises a groove 37 encircling the orifice 36. Thisgroove has a T shaped section and receives the heads of the bolts 38by-means of which the supports 39 for the forming fingers are attached.In the present case these supports 39 are four in number, but may bemore or less in number.

Each support is attached to the plate 27 by bolts 38 which pass throughelongated orifices of circular shape in the supports 39 so that thelatter may be angularly adjusted in a radial plane with respect to theplate.

In like manner the supports 39 which carry the forming fingers 40 may beadjusted in an axial direction by threaded rods 40a.

It will be seen that under these conditions, as many forming fingers asdesired may be mounted and each of these fingers may be set in anyposition necessary to obtain satisfactory regulation of the machine.

FIG. 3 also shows that the circular groove 37 communicates with alateral groove 37a through which the bolts 38 may be introduced.

FIGS. 11 and 12 are two views showing the forming fingers 40 and theadjacent parts of the machine on a larger scale. Thus FIG. 1 1 shows thepart of supports 39 for the forming fingers 40.

FIG. 12 shows schematically in section the tubular member 5 which isbeing made from a strip which, in the present case has a very schematicS shape, and the profile of the forming finger 40 corresponding to thisspecific shape of the strip 9.

FIG. 4 shows in section on a larger scale the upper part of a tubularmember according to the invention made from a strip having a differentshape.

In this case the strip 9 has a generally S shape having two hooked edges9a and 9b which are connected to the main part of the strip 9 by groovedportions 9'a and 9b.

As seen on FIG. 4, the formation of the tubular body is such that ahooked edge 9a of a coil engages in the grooved part 9b of the next coilwhile leaving a little play between the two hooked edges 90 and 9b whichengage each other.

As will be hereinafter explained, these coils are preferably so formedthat the coils have a tendency to press resiliently against each other.It follows that the edge of each coil 9b bears resiliently against thevertical flank of the recess 9'a or 9b of the adjccent coil while Itwill thus be seen that due to the space 41, which leaves a certain playbetween the coils, it is possible to impart to the tubular memberaccording to the invention a relatively great flexibility. However,according to the preferred embodiment of the invention, the coils areresiliently urged against each other so that the tubular memberaccording to the invention has a tendency to spontaneously return to itsstraight form.

The method of making the helical coil of the strip 9 in accordance withthe preferred embodiment of the invention will now be described.

FIGS. 5 and 6 show the first step in the formation of the helical coilaccording to the invention.

FIG. 5 is an elevational view transverse to the axis of a tubular memberbeing formed, and shows the profile of the first coil. In order to makethis, the shaped strip 9 arrives along a straight path 42 after passingthrough the forming rollers which have imparted a curved shape theretoas may be clearly seen in FIG. 6. The forming fingers impose on the part42 which advances in the direction of the arrow F a resilient curvatureat 43, which results in a permanent deformation at 44 correspondingsubstantially to the diameter of the tubular member which is beingmanufactured.

As may be clearly seen on FIG. 6, the arcuate deformation which isimparted to the strip 9 is such that the strip is spontaneouslyhelically wound toward the bottom of the FIG. 6 (arrow F1) in the formof a helix having coils which are not connected to each other.

In order to produce the tubularmember according to the invention, thepart 44 of the strip 9 is caused to cross the first loop formed notbelow, but above (FIG. 6). This begins the coil which is shown in FIG.8.

It will, however, be. appreciated that because of the natural shape ofthe coil which is formed when the helix is .forcibly coiled upwardly,while this helix would be formed spontaneously in a downward direction,the part 44 of the coil which forms (FIG. .8) is elastically urgedagainst the part 42 which forms the previous turn.

FIGS. 9 and 10 show the evolution of the formation of the tubular memberupwardly and it will be seen that when the member 44 has been passedabove the part 42 (FIG. 8), the helical shape which results mustnecessarily continue to be formed in this direction (FIG. 8, FIG. 10).

This results in the formation of a tubular member 5 in which thedifferent turns engage each other as has been clearly explained withreference to FIG. 4, while the turns are urged elastically against eachother by reason of the phenomen which has just been described.

It will also be appreciated that the degree of force by which thedifferent turns of the spiral are urged against each other may beregulated by regulating the directions and magnitudes of thedeformations imposed upon the strip.

The tubular members which are made in accordance with the invention haveparticularly valuable properties for numerous applications, andespecially in the case of flexible tubing for use in drilling oil wells.

It is particularly easy to form the flexible tubular member about thetube of plastic material which is designed to make it fluid-tight.

In like manner, the tubular member has the advantage of offering a greatresistance to internal and extemal pressures even though being veryflexible, which makes it possible to wind the tubular members accordingto the invention on cores of sufficiently small diameter to make themeasy to transport and handle.

it will of course be appreciated that the embodiment which has just beendescribed has been given purely by way of example and may be modified asto detail without thereby departing from the basic principles ofthe-invention.

In particular, it is clear that the sections of the strong steel stripwhich have been shown on the drawings have been given only by way ofexample, and the strip may be given other shapes depending upon thenature and characteristic of the tubular member which is to bemanufactured.

What is claimed is:

1. Method of manufacturing a flexible tubular member by coiling ametallic strip having longitudinally extending abutment means into ahelix having overlapping turns, which method comprises the steps ofimparting an arcuate deformation to said strip such that the edge ofsaid strip which is to be on the outside of the overlapping turns in thecompleted tubular member is longer than the edge of the strip which isto be on the inside thereof, coiling said strip into a helix in which,when said helix is a axially unstressed, the turn last formed lies onone side of the preceding turn, and stressing said strip by positioningthe last-formed turn on'the other side of said preceding turn, with theportion of the of the longitudinal abutment means in each turncontacting a surface on an adjacent turn to resist a return of saidstrip to its unstressed position.

2. Method as claimed in claim 1 in which, when said helix is axiallyunstressed, .the shorter edge of the section of said strip defining saidlast-formed turn lies close to the longer edge of the section of saidstrip defining the preceding turn, and the longer edge of the stripdefining said last-formed turn is adjacent the shorter edge of thesection of said strip defining said preceding turn when said helix isaxially stressed.

3. Method as claimed in claim 1 in which the edges of said strip arehooked in opposite directions and the ad jacent edges of adjacent turnsare hooked over each other to resist separation of said turns axially ofsaid tubular member.

4. Method as claimed in claim 1 according to which said strip is made ofstrong steel.

5. Method as claimed in claim 1 according to which the tubular member isformed about a plastic tube.

6. Flexible tubular member in the form of a helical coil havingoverlapping turns made from an arcuate metal strip, one edge of which islonger than the other, said strip comprising longitudinally extendingabut- 7 wells.

8. Device'for forming a flexible tubular member from a metallic strip ofmaterial having longitudinally extending abutment means which comprisesin combination, means for leading the strip along a plane substantiallyparallel to the axis of the tubular member which is to be formed, meansfor imparting a permanent arcuate deformation to said strip such thatthe edge of the strip in the direction in which the tubular member isbeing formed is longer than the other edge of the strip, means forimparting a helical deformation to said strip to form it into a helixhaving a diameter substantially equal to that of the member beingformed, and for engaging the longer edge of the turn being formed withthe turn which has just been formed, means for guiding the inbularmember thus formed, and means for synchronizing the speed of rotation ofthe tubular member being formed and the feed of the strip from which themember is to be formed.

9. Device as claimed in claim 8 in which the means for imparting anarcuate deformation to the strip comprises a set of rollers which bendssaid strip beyond its elastic limit.

10. Device as claimed in claim 8 in which the means for forming thestrip into a helix comprises a forming head including a plate mounted ona universal joint so that its position m be adjusted about both ahorizontal and a vertical axis.

11. Device as claimed in claim 10 in which the plate comprises a centralorifice through which the tubular member is being formed and that theforming fingers are positioned on the periphery of this orifice bysupports which are angularly and longitudinally adjustable.

12. Flexible tubular member as claimed in claim 6 in which the edges ofsaid strip are booked in opposite directions and the adjacent edges ofadjacent turns are hooked over each other to resist separation of saidturns axially of said tubular member.

13. Device as claimed in claim 8 in which said means for imparting anarcuate deformation to said strip imparts said arcuate deformation in aplane passing through both edges of the strip.

1. Method of manufacturing a flexible tubular member by coiling ametallic strip having longitudinally extending abutment means into ahelix having overlapping turns, which method comprises the steps ofimparting an arcuate deformation to said strip such that the edge ofsaid strip which is to be on the outside of the overlapping turns in thecompleted tubular member is longer than the edge of the strip which isto be on the inside thereof, coiling said strip into a helix in which,when said helix is a axially unstressed, the turn last formed lies onone side of the preceding turn, and stressing said strip by positioningthe lastformed turn on the other side of said preceding turn, with theportion of the of the longitudinal abutment means in each turncontacting a surface on an adjacent turn to resist a return of saidstrip to its unstressed position.
 2. Method as claimed in claim 1 inwhich, when said helix is axially unstressed, the shorter edge of thesection of said strip defining said last-formed turn lies close to thelonger edge of the section of said strip defining the preceding turn,and the longer edge of the strip defining said last-formed turn isadjacent the shorter edge of the section of said strip defining saidpreceding turn when said helix is axially stressed.
 3. Method as claimedin claim 1 in which the edges of said strip are hooked in oppositedirections and the adjacent edges of adjacent turns are hooked over eachother to resist separation of said turns axially of said tubular member.4. Method as claimed in claim 1 according to which said strip is made ofstrong steel.
 5. Method as claimed in claim 1 according to which thetubular member is formed about a plastic tube.
 6. Flexible tubularmember in the form of a helical coil having overlapping turns made froman arcuate metal strip, one edge of which is longer than the other, saidstrip comprising longitudinally extending abutment means, and beingunder an internal tension biassing the shorter edge of each turn of saidcoil toward the adjacent longer edge of an adjacent turn until theabutment means of each turn engages a cooperating surface on an adjacentturn with a force sufficient to cause said turns to reverse theirrelative positions axially of said coil if said reversal were notprevented by said engagement.
 7. A tubular member as claimed in claim 6encircling a fluid-tight tube and adapted for use in drilling oil wells.8. Device for forming a flexible tubular member from a metallic strip ofmaterial having longitudinally extending abutment means which comprisesin combination, means for leading the strip along a plane substantiallyparallel to the axis of the tubular member which is to be formed, meansfor imparting a permanent arcuate deformation to said strip such thatthe edge of the strip in the direction in which the tubular member isbeing formed is longer than the other edge of the strip, means forimparting a helical deformation to said strip to form it into a helixhaving a diameter substantially equal to that of the member beingformed, and for engaging the longer edge of the turn being formed withthe turn which has just been formed, means for guiding the tubularmember thus formed, and means for synchronizing the speed of rotation ofthe tubular member being formed and the feed of the strip from which themember is to be formed.
 9. Device as claimed in claim 8 in which themeans for imparting an arcuate deformation to the strip comprises a setof rollers which bends said strip beyond its elastic limit.
 10. Deviceas claimed in claim 8 in which the means for forming the strip into ahelix comprises a forming head including a plate mounted on a universaljoint so that its position m be adjusted about both a horizontal and avertical axis.
 11. Device as claimed in claim 10 in which the platecomprises a central orifice through which the tubular member is beingformed and that the forming fingers are positioned on the periphery ofthis orifice by supports which are angularly and longitudinallyadjustable.
 12. Flexible tubular member as claimed in claim 6 in whichthe edges of said strip are hooked in opposite directions and theadjacent edges of adjacent turns are hooked over each other to resistseparation of said turns axially of said tubular member.
 13. Device asclaimed in claim 8 in which said means for imparting an arcuatedeformation to said strip imparts said arcuate deformation in a planepassing through both edges of the strip.